Petrolatum and its manufacture were initially patented in 1872 by Robert A. Cheeseborough (U.S. Pat. Ser. No. 127,568). Although Cheeseborough cited treating leather as its primary use, petrolatum was also recommended as a hair pommenade and for treating chapped hands. In 1875, the American Pharmaceutical Association found petrolatum "without a superior" for treating burns and scalds. Since then, petrolatum's beneficial properties for skin care and treatment have been extensively studied and reported.
Petrolatum has been found to be the best material for relieving ordinary xerosis (Morrison et al., Cos & Toil. (1996) 111:59). Petrolatum's moisturizing characteristics have been ascribed to the slowed water loss when petrolatum is applied to the skin. Petrolatum has also been used extensively on wound dressings, both as a treatment and as a pharmaceutically acceptable ointment base to deliver other medicinal compositions.
However, the same hydrophobic properties which make petrolatum an effective moisture barrier, also make it difficult to evenly disperse in fluid aqueous preparations. When mixed with water, petrolatum immediately forms a separate distinct layer. Evenly dispersed fluid preparations are essential for commercial manufacturing techniques, such as spraying. This is true for petrolatum encapsulated in lipid vesicles as well as unencapsulated products.
Accordingly, it is an object of the present invention to provide methods and compositions relating to a sprayable petrolatum product consisting of lipid vesicles encapsulating petrolatum, dispersed in an aqueous phase.
Another object of this invention is to provide a stable dispersion of petrolatum containing lipid vesicles in water.
These and other objects and features of the invention will be apparent from the following descriptions.